Laser screens for cathode-ray tubes are known to have an optical cavity with a semiconductor member between the mirrors defining the cavity (V. I. Kozlovsky et al. Laser Screens of CdS, CdS.sub.x Se.sub.1-x and ZnSe Monocrystalline Ingots (in Russian). J. Kvantovaya Elektronika. Moscow. 1977. Vol. 4. No. 2. p. 351-354). The optical cavity is cemented to a transparent heat removing support member. Organic adhesive compositions are used to cement the optical cavity to the transparent support member. This laser screen cannot work with an acceptable efficiency for a long time at temperatures close to room temperature. If thickness of the single-crystal wafer is much greater than the typical depth of penetration of an electron beam into the laser screen, a strong absorption in the non-excited zone of the single-crystal wafer substantially lowers efficiency of lasing at room temperature. If the thickness of a single-crystal wafer is approximately the depth of the penetration of an electron beam into the laser screen, the efficiency of the laser screen remains high even at room temperature. However, service life of such laser screens is rather short because of a rapid decomposition of an organic cementing layer under the action of an electron beam partly penetrating the cementing layer if a small-thickness wafer is used. The service life is also shortened because of thermoelastic stresses at the boundary between the single-crystal wafer and cementing layer due to a low heat conductance of the cementing layer.
It is known to make a semiconductor laser with optical pumping, comprising a multiple-layer structure which consists of an active layer, reflecting layers, and a passive single-crystal epitaxial layer having different values of the bandgap width and different indices of refraction (Jewell, J. L. et al. Vertical Cavity Single Quantum Well Laser. Appl. Phys. Lett. 1989. Vol. 55. p. 424). This structure can be used as a laser screen for a cathode-ray tube. This device does not have a cementing layer because one layer of the structure is made thick enough to function as a heat removing support member. In addition all layers, including the mirror layers defining an optical cavity, are single-crystal layers. A structure like this is prepared by a method comprising epitaxial overgrowth of layers of different composition from organoelement compounds (Koyama F. et al. CaAlAs/GaAs MOCVD Growth for Surface Emitting Laser. Jap. J. of Appl. Phys. 1987. Vol. 26. No. 7. p. 1077-1081). This method can only be carried out with a high perfection of structure of grown substrates and fair agreement between parameters of lattices of all grown single-crystal layers. This surface emitting laser structure is also deficient in the fact that it can be grown only with the use of a limited number of A.sup.III B.sup.V semiconductor compounds emitting only in the near infrared spectral area. These compounds cannot be used for lasing in the visible spectral area.
Another prior art laser screen has a transparent support member and a structure having a silver mirror coating, a semiconductor layer, a passive transparent semiconductor layer, and a partly transparent mirror which is cemented to the transparent support (Katsap, V. N. et al. Heterostructures Cd.sub.x Se.sub.1-x /CdS in Longitudinal Electron Beam Pumping Lasers (in Russian). J. Kvantovaya elektronika. Moscow. 1987. Vol. 14. No. 10. p. 1994-1997). A method for making this laser screen involves polishing a wafer having an appropriate orientation on the one side, overgrowing on this side a passive layer of a similar semiconductor compound having a wider bandgap, applying a partly transparent insulating coating to this layer, cementing the resulting structure to a support, polishing the opposite side of the wafer, and applying a reflecting mirror to this opposite side of the wafer. The passive layer is grown by static resublimation in a quasi-sealed space at 1175 to 1225K in argon or hydrogen. The boundary between the wafer and the passive layer in this laser screen is within the optical cavity formed by the partly transparent mirror and reflecting mirror. This method can be used for making laser screens of A.sup.II B.sup.VI semiconductor compounds which radiate in the visible and near ultraviolet spectral areas. The passive layer thickness must be large enough because the cementing layer should be spaced to a desired distance from the zone excited by electron beam which is necessary to prolong service life. In addition, the bandgap width of the passive layer must be large enough in comparison with the bandgap width of the active layer so as to lower absorption in the passive layer. It is, however, difficult to overgrow the passive layer of such compounds by the procedure described above without impairing emitting efficiency of the active semiconductor. This results in the prior art laser screen having a low lasing efficiency at room temperature.